Arc-extinguishing unit and contact structure for a circuit interrupter



W. H. FISCHER ARC-EXTINGUISHING UNIT AND CONTACT STRUCTURE Aug. 4, 1964 FOR A CIRCUIT INTERRUPTER Filed Oct. 28, 1960 3 Sheets-Sheet 1 Fig. 3

g- 4, 1964 w. H. FISCHER 3,143,622

ARC-EXTINGUISHING UNIT AND CONTACT STRUCTURE FOR A CIRCUIT INTERRUPTER Filed Oct. 28, 1960 v 3 Sheets-Sheet 2 24b 24o 7 24a Fig. 2

w. H. FISCHER 3,143,622 ARC-EXTINGUISHING UNIT AND CONTACT STRUCTURE FOR A CIRCUIT INTERRUPTER v 3 Sheets-Sheet 3 lll l 7 5 s r 4 H 0 9 I O 3 5 u 7 M 6 m F 9 3 8 7 7 7 1 J 5 2 l I 6 7 5 .H. 7 5 w v 4 N v I w 5 7 8 7 7 I. I 8 I T Aug. 4, 1964 Filed 0011.28, 19s0 United States Patent 3,143,622 ARC-EXTINGUISHING UNIT AND CONTACT STRUCTURE FOR A CIRCUIT INTERRUPTER William H. Fischer, Avalon, Pa, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 28, 1960, Ser. No. 65,653 Claims. (Cl. 200-145) This invention relates to circuit interrupters in general, and, more particularly, to circuit interrupters of the fluidblast type. t A general object of the present invention is to provide an improved circuit interrupter of simplified construction in which fluid-blast action is obtained with a minimum of moving parts, and highly eifective interrupting action is obtained over a wide current range.

A more specific object of the present invention is to provide an improved fluid-blast circuit interrupter of the type involving a pair of serially related arcs, one of which is preferably a pressure-generating arc and the other is an interrupting arc.

Still a further object of the present invention is to provide an improved double-break circuit interrupter in which only a single moving contact is employed, and yet a pair of serially related arcs is established.

A still furtherobject of the present invention is to provide an improved fluid-blast circuit interrupter in which a more eifective streamline flow of interrupting fluid is obtained at the interrupting arc as a result of pressure generated at the pressure-generating arc.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

FIGURE 1 is a side elevational view of a circuit interrupter embodying the invention;

FIG. 2-is a fragmentary enlarged vertical sectional view of the arc-extinguishing structure of the circuit interrupter shown in FIG. 1, the parts being shown in the closedcircuit position;

FIG. 3 is a fragmentary, considerably enlarged vertical sectional view taken through the improved arc-extinguishing unit of the present invention, the contact parts being illustrated in the partially open-circuit position;

FIG. 4 illustrates a modified type of arc-extinguishing unit, again the contact structure being illustrated in the partially open-circuit position; and,

FIG. 5 illustrates a slight modification of the interrupting structure of FIG. 4, again the contact structure being illustrated in the partially open-circuit position.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates supporting means disposed at ground potential and comprising a plurality of vertically extending channel members 2 braced by diagonally extending supports 3. The supporting means 1 is supportedon a base 4. The supporting means 1 rigidly supports in place a circuit interrupter 5 having an upper line terminal 6 and a lower line-terminal 7. The conductors 8, 9 connect the circuit interrupter 5 into the electrical circuit to be protected.

Referring more particularly to FIG. 2, it will be observed that the circuit interrupter of our improved conwashers 15, the inner ends of which are forced by bolts 16 toward a casting member 17.

The casting member 17 is supported by a cylindrical ice insulating tube 18. The upper end of the tube 18 is supported by a ring-shaped member 19 secured by bolts 20 to a metallic ring 21. The metallic ring 21 is secured to a support member 22 by welding or the like, the upper end of the support member 22 in turn being secured to one or more channel members 23 forming a part of the support means 1. A plate 24 is secured by suitable means, not shown, to the support member 22 and supports a high-voltage terminal bushing, generally designated by the reference numeral 25, preferably of the condenser-type, intermediate the ends thereof. More specifically, the plate 24 is attached by bolts 24a to a metallic support member 24b, the latter supporting an insulating cylinder 25a, through which extends a conducting tube or elongated conductor 25b. Thus the'conducting means 28 for the circuit interrupter including the tube 25b extends through the support means 1 by means of the high: voltage condenser bushing 25.

An arc-extinguishing unit, or an extinguishing means, generally designated by the reference numeral 26, is disposed adjacent one end of the conducting means 28 extending through the bushing 25, and terminal means 27 for the interrupter is positioned adjacent the opposite side of the arc-extinguishing unit 26 from the conducting means 28. V

The longitudinally extending conducting means 28 comprises contact means including a movable rod-shaped contact 29 having a rack 30 formed on its right side, as viewed in FIG. 2, and biased downwardly toward the closed position by a compression spring 74 disposed in the conducting tube 25b. A gear 31 meshes with the rack 30 to cause the actuation of the same. Secured to the gear 31 is a pinion 32, the gear and pinion being supported on a pin 33, which passes through two opposed vertically extending support plates 34, 35 carried on the end of the bushing 25, as more clearly shown in FIG. 2.

Meshing with the pinion 32 is a gear segment 36 secured to an arm 37, the latter being pivoted on a bolt 38 and having an integrally formed sleeve portion 39. The sleeve portion 39 has an operating arm 40 integrally formed therewith, which makes pivotal connection at 41 to an operating rod 42 formed of a suitable insulating material. The operating rod 42, it will be noted, extends substantially longitudinally of the conducting means 28 and is actuated by a lever 43 making pivotal connection to the operating rod 42 at 44. A shaft 45 serves to rotate the lever 43 and hence to effect reciprocating, substantially vertical motion, of the operating rod 42. Preferably, a bumper mechanism 46 is provided, assuming in this instance the form of a compression spring 47 encircling a rod 48 and seating upon a washer member 49 actuated vertically by a portion 50 of the lever 43.

Surrounding the bushing 25 is a current transformer winding 51 to serve as a measure of the magnitude of the current passing through the interrupter. The winding 51 is connected to suitable measuring equipment, which will actuate suitable relays, not shown, in response to overload conditions existing in the circuit connected to the interrupter.

From the foregoing description, it will be apparent that the spring vwashers 15 place the poreclain casing 11 in compression and also place the insulating cylinder .18 in tension. Preferably a suitable arc-extinguishing fluid 52 fills the casing 18.

With reference to FIG. 3, which more clearly shows the internal construction of the arc-extinguishing unit 26, it will be noted that cooperable with the movable contact 29 is a relatively stationary intermediate contact 54 having two contact tip portions 55, 56. To support the intermediate contact 54 in a fixed, substantially central position a metallic L-shaped bracket member 54a is brazed, or otherwise secured to intermediate contact 54. Bolts 54b extend through the wall of the interrupter tube, as shown, to secure the L-shaped bracket 54a fixedly in position. The lower tubular end 57 of the movable tubular contact 29 slides over the relatively stationary inter- 'mediate contact 54, in enveloping fashion, to engage the lower relatively stationary contact structure, generally designated by the reference numeral 58. A slot 29a in the tube 29 registers with the relatively thin bracket member. 54a.

Preferably, the relatively stationary contact structure includes a plurality of segmental fingers 59 biased 4 rent being interrupted and also to improve the power factor of the circuit.

In addition to the use of the resistance 73, associated with the relatively stationary intermediate contact 54, there may also be employed an impedance means 76 associated with the relatively stationary contact structure 77 to insert additional impedance, such as resistance, into the circuit to facilitate interruption. Otherwise, the operation of the modified type interrutping unit 78 of FIG. 4 is identical to that previously described in connection with FIG. 3 of the drawings.

As shown in FIG. 4, the imepdance means 73, 76 may constitutea plurality of carbon-impregnated blocks of :to the relatively stationary contact structure 58 and thence tween the lower arc-resisting portion 66 of contact 29 and the upper arcing tip portion 55 of the intermediate contact 54, as shown in FIG. 3. The fluid 52, which fills the interrupting chamber 67, constituted by an insulating casing 68 and an upper closure member 69, having an orifice 70, causes the fluid 52 to be placed under pressure by the pressure-generating are 64.

The generation of pressure within the arcing chamber 67 by the establishment of the pressure-generating are 64 will cause the fluid to flow upwardly under pressure, indicated by the arrows 71, through the orifice opening ,72 and into intimate engagement with the interrupting arc 65 drawn between the contacts 29, 54 to effect the extinction thereof.

It will be observed that the tip portion 55 of the relatively stationary intermediate contact 54 is positioned at an effective location within the orifice restriction 72 to effectively receive the full effect of the fluid blast exhausting out of the interrupting unit 26.

, Where a highly effective arc-extinguishing gas, such as sulfur hexafiuoride SP is employed, preferably the orifice member 70 and the interior walls of the insulating casing 68 are lined with a suitable arc-resisting material, such as polytetrafluoroethylene, as set forth in United 'States Patent 2,757,26 l ,'issued July 31, 1956, to Harry J.

Lingal, Thomas E. Brown, Jr. and Albert P. Strorn, and i assigned to the assignee ofthe instant application.

It will be observed that only a single movable element,

namely the movable tubular contact 29 need be employed with the present construction. Despitethe fact that only a single movable element 29 is employed, nevertheless, as shown, two series arcs 64, are established very rapidly,

the interrupting arc 65 receiving the full effect of the which an impedance means, such as a resistance 73 is interposed between the arcing tip portions 55, 56 of the relatively stationary intermediate contact 54. This will insert the resistance 73 into series circuit during the opening operation to reduce the magnitude of the cura type well known by those skilled in the art. The individual carbon-impregnated blocks 78 may be held in position interiorly within an insulating tube 79, constituting a part of the relatively stationary intermediate contact structure 54.

FIG. 5 illustrates a construction involving a slight departure from the construction illustrated in FIG. 4 by positioning. the impedance means, or resistance 73' externally of the interrupting. chamber 67. For certain applications, it may be preferable to position the impedance means 73' externally of the interrupter for constructional reasons. Otherwise, the operation and function of the modified interrupting unit 79 of FIG. 5 is identical to that set forth in FIG. 4.

From the foregoing description, it will be apparent that there is shown and described an improved simplified type of interrupting structure, in which only a single relatively movable part 29 is employed, the remaining portions of the interrupter being relatively fixed. The movement of the movable tubular contact 29, in enveloping fashion, over the intermediate contact 54 in sliding manner may be employed to clean the external surface of the intermediate contact 54. In addition, the intermediate contact 54 may be positioned in the most optimum location relative tothe orifice opening 72 of the orifice member 70 to most effectively receive the blast of fluid exhausting from .the interrupter chamber 67 The arc-extinguishing fluid may be either a liquid or a gas, as desired. The construction is novel in that it ohtains two series breaks with only one moving contact. The intermediate contact being relatively stationary, the moving contact rapidly travels to the open-circuit posi- :tion with the arc transferring to the intermediate contact 54., Such an arrangement eliminates the need for a cluster of fingers at the orifice entrance, and, in addition, the construction allows a more streamlined flow of the gas through the orifice opening 72. Closing is made easier since the moving contact 29 does not have to compress an intermediate contact spring, which is normally 73 may, instead of being formed of carbon blocks, be

constructed of a heavy wire Wound into a coil. The insertion of the impedance means into the circuit reduces the current magnitude and facilitates interruption by improving the power factor of the circuit. Again the pressure generated at the lower break of the interrupting devices of FIGS. 4 and 5 is employed to exhaust out through the orifice opening 72, extinguishing thereby the are 65 at the upper interrupting break. As shown, the hollowed portion of the moving contacts 29 is split into cantilever contact fingers 29a, which rub upon the stationary intermediate contact 54 as the movable contact 29 passes over it in moving to the open-circuit position. Among the advantages of the present invention is that of mechanical simplicity. Another advantage is the insertion of a series resistor during interruption to reduce the current. Still a third advantage is the fact that the moving contact 29 may function as a stopper in the orifice opening 72 thereby allowing the pressure within the interrupting chamber 67 to build up before the moving contact 29 unplugs the orifice opening 72 and thus permits the exhausting of the fluid blast out of the interrupting chamber 67 to effect extinction of the interrupting are 65.

Although there are illustrated and described several interrupting arrangements, it is to be clearly understood that the same are merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

I claim as my invention:

1. The combination in a fluid-blast circuit interrupter of means at least partially of insulating material defining a substantially enclosed interrupting chamber, said interrupting chamber being provided with an orifice opening, a relatively stationary contact disposed within said interrupting chamber, a relatively stationary intermediate contact spaced from said relatively stationary contact and also disposed within said interrupting chamber, impedance means connected between the ends of the relatively stationary intermediate contact, a tubular movable contact sliding over the relatively stationary intermediate contact to engage the relatively stationary contact in the closed-circuit position of the interrupter, the tubular movable contact withdrawing through the orifice opening during the opening operation so that fluid under pressure may blast out of the orifice opening to effect circuit interruption, and the arrangement functioning to establish a pair of serially related arcs during the opening operation.

2. A circuit interrupter of the two-break type including a relatively stationary contact, a relatively stationary intermediate contact spaced from said relatively stationary contact, impedance means disposed between the ends of the relatively stationary intermediate contact, a tubular movable contact sliding over the relatively stationary intermediate contact to engage the relatively stationary contact in the closed-circuit position of the interrupter, the impedance means being inserted into series circuit during the opening operation to reduce the magnitude of the interrupted current and to improve the power factor, the arrangement functioning to establish a pair of serially related arcs during the opening operation, means defining a substantially enclosed interrupting chamber having an orifice opening, said relatively stationary and intermediate contacts being disposed interiorly of said substantially enclosed interrupting chamber, and said movable tubular contact being movable through the orifice opening to draw an arc therethrough.

3. The combination in a substantially enclosed fluidblast circuit interrupter of a tubular casing having an orifice member adjacent one end thereof, and a relatively stationary contact adjacent the other end thereof, a bracket member extending laterally inwardly from the inner side wall of said tubular casing, a rod-shaped stationary intermediate contact supported by said bracket member, impedance means serially connected between the ends of the stationary intermediate contact, a tubular movable contact having a slot along one side thereof movable over the stationary intermediate contact into engagement with said relatively stationary contact, and the arrangement functioning to draw two series arcs with one are being drawn through said orifice member.

4. The combination in a fluid-blast circuit interrupter of a substantially enclosed tubular casing having an orifice member adjacent one end thereof and a relatively stationary contact adjacent the other end thereof, a bracket member extending laterally inwardly from the inner side wall of said tubular casing, a rod-shaped stationary intermediate contact supported by said bracket member, impedance means serially connected between the ends of the stationary intermediate contact, a tubular movable contact having a slot along one side thereof movable over the stationary intermediate contact into engagement with said relatively stationary contact, the arrangement functioning to draw two series arcs with one are being drawn through said orifice member, and said impedance means being positioned externally of the tubular casing.

5. A fluid blast circuit interrupter including a substantially enclosed tubular insulating casing, an orifice memher having an orifice opening closing one end of said casing, a closure member supporting a relatively stationary contact structure closing the other end of said tubular casing, the relatively stationary contact structure including a centrally disposed upstanding arcing contact and a plurality of circumferentially-disposed main finger contacts, means biasing the main finger contacts radially inwardly toward the arcing contact, a bracket member extending inwardly from an inner side wall of the casing, a rod-shaped stationary intermediate contact supported by said bracket member and spaced from said relatively stationary contact structure, impedance means connected between the end tip portions of said stationary intermediate contact, a tubular slotted movable contact movable through said orifice opening and over the rod-shaped intermediate contact in enveloping fashion into contacting engagement with said main finger contacts, and a pair of serially related arcs being established during the opening operation with one of said arcs being positioned at the orifice opening to receive the fluid blast generated by the other are within the casing.

References Cited in the file of this patent UNITED STATES PATENTS 2,073,565 Ruppel Mar. 9, 1937 2,155,276 Kornadorfer Apr. 18, 1939 2,324,047 Van Ryan July 13, 1943 2,365,132 Amer et al. Dec. 12, 1944 2,529,145 Fernier Nov. 7, 1950 2,665,351 Forwald Jan. 5, 1954 FOREIGN PATENTS 668,105 Germany Nov. 26, 1938 111,010 Sweden June 27, 1944 

1. THE COMBINATION IN A FLUID-BLAST CIRCUIT INTERRUPTER OF MEANS AT LEAST PARTIALLY OF INSULATING MATERIAL DEFINING A SUBSTANTIALLY ENCLOSED INTERRUPTING CHAMBER, SAID INTERRUPTING CHAMBER BEING PROVIDED WITH AN ORIFICE OPENING, A RELATIVELY STATIONARY CONTACT DISPOSED WITHIN SAID INTERRUPTING CHAMBER, A RELATIVELY STATIONARY INTERMEDIATE CONTACT SPACED FROM SAID RELATIVELY STATIONARY CONTACT AND ALSO DISPOSED WITHIN SAID INTERRUPTING CHAMBER, IMPEDANCE MEANS CONNECTED BETWEEN THE ENDS OF THE RELATIVELY STATIONARY INTERMEDIATE CONTACT, A TUBULAR MOVABLE CONTACT SLIDING OVER THE RELATIVELY STATIONARY INTERMEDIATE CONTACT TO ENGAGE THE RELATIVELY STATIONARY CONTACT IN THE CLOSED-CIRCUIT POSITION OF THE INTERRUPTER, THE TUBULAR 